Molecular structure, spectroscopic studies (FTIR, FT-Raman and NMR) and HOMO–LUMO analysis of 6-chloro-o-cresol and 4-chloro-3-methyl phenol by density functional theoretical study

In this work, the experimental and theoretical vibrational spectra of 6-chloro-o-cresol (COC) and 4-chloro-3-methylphenol (CMP) have been studied. FTIR and FT-Raman spectra of the title compounds in the solid phase are recorded in the region 4000–400 cm−1 and 4000–50 cm−1, respectively. The structural and spectroscopic data of the molecules in the ground state are calculated by using density functional methods (B3LYP) with 6-31G* basis set combinations. The calculated vibrational frequencies are scaled by normal coordinate analysis based on a scaled quantum mechanical force field. The obtained values are compared with experimental FTIR and FT-Raman spectra. The observed and calculated frequencies are found to be in good agreement. The complete vibrational assignments are performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. The results of 13C and 1H NMR chemical shift are compared with the experimental values.

Graphical abstractIn this work, we reported a combined experimental and theoretical study on molecular structure, Vibrational spectra, HOMO, LUMO, NMR analysis of 6-chloro-o-cresol and 4-chloro-3-methylphenol.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► COC and CMP are used as disinfectants and deodorizers. ► Simulated and observed vibrational spectra are agreed well. ► 1H and 13C NMR chemical shifts have been compared with experimental values. ► The HOMO–LUMO energy gap of COC and CMP are 0.218 and 0.211 a.u.